This invention relates generally to generators used in eddy current retarding systems. More specifically, this invention relates to reluctance generators used in eddy current braking systems for vehicles.
Vehicles use brakes and similar retarding systems to decelerate. Vehicles include automobiles, trucks, buses, and the like. Friction braking or deceleration systems typically include drum or disc systems. Drum systems use traditional wear pads. Disc systems have a friction rotor/stator arrangement. Both systems have components that require periodic maintenance. Normal wear and tear of the friction components in these systems often results in periodic and expensive repairs. Failure to check and repair or replace worn components can result in damage to the braking system and to the vehicle. Additionally, these systems convert kinetic energy from the wheels and axles into heat, which increases the wear of the brake pads or discs.
Many vehicles use electromagnetic retarders for braking and deceleration systems. Electromagnetic retarders often use an electric generator to retard the rotation of an axle or a drive shaft, which also is the rotor for the generator. During non-braking periods, the generator may generate electricity from the energy generated by the spinning axle. The electricity usually to recharges a battery such as in a regenerative braking system. The energy also may be dissipated as heat especially when there is a large amount of kinetic energy or torque to convert to electrical energy or heat. To decelerate or brake, the electric rotor or generator applies reluctance from a stator to the rotor. The application of the reluctance on the stator creates eddy currents in the rotor. The eddy currents reduce or slow the rotation of the rotor, which decelerates the vehicle.
The invention provides a reluctance generator for an eddy current braking system in a vehicle where a magnetomotive force induced by a compensation winding balances the magnetomotive force generated by a rotor.
In one aspect, a reluctance generator for an eddy current braking system in a vehicle has a stator assembly and a rotor. The stator assembly defines a core space and has a field winding and a compensation winding. The field winding is operable to induce a field magnetomotive force (MMF) in response to a first excitation. The compensation winding is operable to induce a compensation magnetomotive force (MMF) in response to a second excitation. The rotor is disposed in the core space and is operable to generate an armature magnetomotive force (MMF). The compensation MMF balances the armature MMF.
In another aspect, a reluctance generator for an eddy current braking system has lamination sections, a field winding, a compensation winding, an armature winding, and a rotor. The lamination sections are disposed along an interior surface of a stator assembly. The lamination sections define a core space and a winding volume. The field winding is disposed along an outer portion of the winding volume. The field winding is operable to induce a field magnetomotive force (MMF) in response to a first excitation. The compensation winding is disposed along an inner portion of the winding volume. The compensation winding is operable to induce a compensation magnetomotive force (MMF) in response to a second excitation. The armature winding is disposed in the lamination sections. The rotor is disposed in the core space. The rotor has a first section and a second section disposed on opposite sides of a center ring mounted on a shaft. The center ring is aligned with the excitation and compensation windings. The rotor is operable to generate an armature magnetomotive force (MMF). The compensation MMF balances the armature MMF.
Other systems, methods, features, and advantages of the invention will be or will become apparent to one skilled in the art upon examination of the following figures and detailed description. All such additional systems, methods, features, and advantages are intended to be included within this description, within the scope of the invention, and protected by the accompanying claims.